How computers use binary to represent data and instructions
PC’s use binary to store data the base value of it is 2 so its digits are 0 and 1 a bit is the smallest amount and a binary number is made of bit for example 0101. The 0’s and 1’s shows the on and off state of a transistor. Programs are sets of instructions the instruction is translated into machine code and binary codes that activate the CPU. That means the programmers that write code, their code is translated to binary instructions, any information really, is stored in binary
How to convert between binary and denary whole numbers (0–255)
When converting Binary into decimal add headers to it and the first one to the right should be 1 and it should keep on doubling, once done that, add up the headers with 1 underneath them and you should get the result. To reverse the process (Decimal to Binary) this is done from left to right. For example say you have £75 you would first make a table with headers above saying what number it is, then you would have 128 as your first one so you put a 0, but then you have 64 and that is enough so you put 1 and subtract 64 from the total amount making the amount left 11, the answer would be 01001011.
How to perform binary arithmetic and the concept of overflow
A left shift doubles the binary values	0001 1010 = 26		0011 0100 = 52                                                                     As you can see one left shift doubled the amount and if we shifted it twice, we’d quadruple it and if we did it 3 times sextuple it? This would also be the same with a right shift but instead divide it. When it is an odd number however it will be rounded down. When adding binary numbers you need to remember 4 rules which is 0+0=0	1+0=1	1+1=10(0, carry 1)	1+1+1=11(1, carry 1) That means when we are adding numbers together we need to work from right to left as usual. If the answer is more bits than both added together it can cause an overflow which will either crash the program or the extra value will be cut off showing the wrong answer.
An overflow can be shown in the sum 11111111 + 1 where the answer would require more bits to not cause an overflow, the CPU drops the overflow digit because the number cannot be stored anywhere so it thinks 255 + 1 = 0 (denary) most CPU’s in 2019 have a 64 bit CPU so it can handle numbers up to 18 quintillion
Why hexadecimal notation is used.
Hexadecimal is used to simplify binary; this means that computers do not actually understand hexadecimal. Hex is often used in things like colour references of error message codes, which can be long. If it weren't for hex. Colour is told by #RRGGBB (Red, Green, Blue) the # says that the code is hex. Each Hex is 4 bits which mean each colour can be 256 ways for example Red. In errors, the number refers to the memory location of the error which helps programmers. To convert the hex to binary you need to know what the 16 characters are, 0-9 is the same as the number however for 10-15 it uses alphabet, up to F. When you have the right amount, you can convert the hex say A which = 11 so you write out 11 in Binary.
Understand how computers encode characters using ASCII.
Characters are stored as a binary number on a computer system. It is important that those characters are the same when say transferring a text file or email. In order to allow for data exchange between PC’s, character sets were made, it’s a table that maps a letter to a unique number one is called ASCII, using the set, “A” Would be set as 10000001 (8 bits are used for every one) however it can only store 128 characters so more character sets are available for more characters, now there is Unicode which has everything from emoji’s to just unused things.
Understand how bitmap images are represented in binary.
There are 2 types of images, Raster and Vector. Raster (also known as bitmap) are made up of pixels (dots that are different colours) They are not scalable, so making them large will blur them. Data is stored on each pixel so it will be larger than vector graphics. Screenshots are raster images for example. Vectors use objects like lines and shapes, that are used mathematically to make the image, you try to make them larger there will be no loss in quality, they are generally smaller than raster, these can be found in things like logos and cartoons. To calculate a picture file size, you can use File Size = Resolution x Colour Depth.
Understand how sound, an analogue signal, is represented in binary

Sound on a PC must be changed from analogue to digital waves, to convert it to digital waves, the sound is sampled using an analogue to digital converter, and then stored as a binary value, the higher the sample rate the more sound is taken. So, programmes such as discord won't be that good because it is trying to compress the audio. The more bit depth the higher the quality will be, this means the file size will also be bigger.
Understand the need for data compression and methods of compressing data
We need to compress a file because it takes up less storage, so more files can be stored, for a page like YouTube it would save money. There are 2 methods Lossless and Lossy, lossless compresses the file then decompresses it when it is opened. Lossy is a file compressed to a smaller size too, but some data is removed to decrease the size, and it doesn’t get uncompressed this works with anything that can be compressed.
Understand that file storage is measured in bytes and be able to calculate file sizes
The size of a file and a devices capacity will always be written in its simplest for. Ex, Windows would show the hard drive as being 1TB when it is 1024 GB, although both are correct.
Understand the characteristics of structured and unstructured data
Databases store data in a structured/organised format, they are used in many ways from phone numbers in your contacts to what you do on the internet cough Facebook cough. Things that are unstructured is when it isn't recorded in an organised manner.

Understand that data can be decomposed, organised and managed in a structured database (tables, records, fields, relationships, keys)
A database table should always contain a key field is a unique identifier for each record, like a name or a group. Databases store data in table and a table can contain many records, each of which can have many fields. A database stores forms to fill data, to display data, to represent in a report.
A relational database has more than one table and the tables are linked using key fields. For example, a library database could have three tables, customer, book and lending when a customer joins a record is created it registers their name and id’s.
A database relationship is a link between different tables, there are 3 types, one to one, this is rare. In a library example, a customer would have a one-to-one relationship with their unique customer ID number. One to many, for ex, a customer might take out many books, there is also many to many. This relationship is implemented in a linked table, with many books being loaned to many customers.
The advantages of a relational database are that the books details and customers details are only entered once, meaning less mistakes are to happen. The database stays relatively small.

TOPIC 4: COMPUTERS
Understand the input-process-output
All modern Computers work on the input-process-output, the way it works is that computer receives an input, processes the information, then performs an output. In a phone it’d do this, type in the message press send, process the phones hardware and network process the message, then output the message gets delivered.
Understand the function of the hardware components of a computer system
The way a PC is designed and laid out is known as its architecture, primitive computers were used to do the same tasks repeatedly. John Neumann came up with an architecture which is still used today and it stored both instructions and data in the memory being able to store programs in the memory allows computers to be reprogrammed for other tasks – this allows us to multi-task and run several programs at the same time. The faster the CPU the faster tasks will perform 3 things that effect the performance of the CPU, these 3 are Cache Memory Clock Speed and Cores. The motherboard is the main circuit of a computer and is unique for each device. A GPU is a processer that produces graphical images to a monitor. In the old days the CPU could be able to produce these graphical images, but as time went on it was created to focus just on graphical processing. It is used by professionals but on laptops they use integrated graphics which relies on memory. Sound cards convert digital data into analog sound waves to output, these are usually integrated in the motherboard on modern PC’s
Understand the function of different types of main memory like RAM and ROM
Primary storage is internal storage which can be accessed by the CPU directly, so access speeds are quick, storage is split in 2 types – volatile and non-volatile, if its volatile the data is lost when the power is turned off, vice versa. There are 4 types of primary storage, RAM, ROM, Cache Memory, Flash memory.
Understand the concept of a stored program and the role of components of the CPU
Instructions and data are transferred between components in circuits called buses, they are restricted by their width, they are 8, 16 or 32 bits wide, the larger it is, the more bits sent at once. The FDE cycle is a sequence of steps that a CPU performs again and again and again to processes the currently running programs. The first thing you need to understand is that the PC register stores the address of where in the ram the next instruction is, here’s how it goes:
Step 1 The Program Counter (PC) register is checked to find the address of the next instruction
Step 2 The instruction is fetched from this address in RAM and transferred into the Current Instruction Register (CIR)
Step 3 Once an instruction has been fetched the PC increases by 1 to show the next instruction
Step 4 The instruction is decoded by the control unit to understand what actions must be taken
Step 5 The instruction is executed using the relevant components e.g.  ALU adding values together

Understand how data is stored on physical devices
Secondary storage is non-volatile storage used to hold data that can be accessed repeatedly. Because secondary storage is further from the CPU and often external longer to access then primary storage. Magnetic Storage: Traditional computers contain a hard disk which is magnetic storage, there are 2 heads that spin to access data and write data, they have large storage.
Optical Storage: Uses laser technology to project beams of light onto a disk if light is reflected back data is recorded as 1 none records 0. Modern disks like Blu-ray has up to 50 GB of storage, on the other hand a CD has 650 MB.
An SSD has no moving parts, it has low power usage and quick access speed, and is increasingly popular and becoming more primary.
Understand the concept of cloud storage
When data is stored in the cloud it is stored on servers that can be accessed with any computer that has an internet connection. Google and Dropbox which are popular charge to store more than the free limit they provide.
Understand the need of embedded systems
An embedded system is a small computer inside of a larger device that performs a specific task, embedded systems are designed to be small and have a lower cost, therefore mass production of them can save money. They are dedicated (single task) the instructions are stored in ROM so it cannot be changed.
Know what an operating system is and how it manages files, processes, hardware and the user interface
An operating system is software that manages a computer system. The operating system is loaded by the BIOS, one of its primary functions is to manage resources some ways how is managing input and output, manage printing, managing backing, manage the RAM, manage processes and manage security, these things usually come for free with no cost with the OS unless you want better antiviruses. Another job for the OS is to provide a user interface. This can be touch, voice controlled a Graphical User Interface or command line.
Understand the purpose and functions of utility software
Antivirus software monitors your computer for any incoming viruses, the antivirus has signature of the virus and is known to the antivirus. That’s why there are updates to antiviruses very regularly. Firewall is a software that analyses packets of data to determine whether they should be allowed or not, it sees where it has come from and where to and figures if its right or not. Files are stored on computer systems that can, over time, become fragmented. This means that they are split and stored on different parts of the disk. If a file is fragmented, it takes longer for the disk heads to move between parts of the file, which slows the process of loading it. Defragmentation is the process where files are physically re-arranged on disk so that they are no longer fragmented, and the parts of each file are stored together. This improves the speed of accessing data from disk. Things like task manager are types of applications allow users to monitor system resources and see the processes that are currently running.  Users will be able to see which programs are being executed and how much CPU time they are requiring.  If a program has stopped responding, or is using too many resources, the user can close it. You can backup data using System backup software in case your original data is lost
Understand how software can be used to simulate and model aspects of the real world
Programmes can be used to create models that help understand and improve real world simulations these programmes usually have large data sets, it can help simulate tension on a bridge.

TOPIC 6: THE BIGGER PICTURE
Understand the environmental impact of technology
In the last 30 years the use of technological devices has increased drastically, and these devices usually require some rare materials, and these devices are thrown away causing eyesore and pollution, because hazardous chemicals are released. This does not help with the increased population over the world meaning more people will be using technological gadgets and materials will become more depleted, however there are some positives of gadgets such as video messengers which can provide for example a meeting without having to travel by a plane etc. and smart devices can save energy and use less. Scientists can also use research databases to study.
Understand the ethical impact of using technology
The term Digital Divide relates to the difference to those who have modern tech compared to those who don’t, the reason it is important is because it is causing countries with limited digital infrastructure, harder times the UN said that internet prices are increasing in low developing countries
Drones: they are a unmanned radio controlled aerial vehicle that is flown remotely, near or far, they have good benefits like preventing pollution and help endangered species, however there have been stories of drones breaking into prison to bring confiscated items, and being used in war from thousands of miles away.
Self-Driving Cars: A self-driving car navigates along a road without any human interaction therefore no need for a driver. Fully automatic cars are still in the works, it will apparently be more fuel efficient and safer.
AI: AI means artificial intelligence and it refers to computers making decisions and performing action without human interaction. This can range from captchas to smart homes, it is becoming more intelligent as we go. People are scared that AI could harm humans but this belief is popularised from the movies.
Privacy and Hacking: Privacy is a massive issue now concerning the internet. In 2014 the government changed the Computer Issue Act to legally allow organisations like MI6 and GCHQ to hack computers, which they had been supposedly doing secretly for years anyway. This change was done with no public debate, Apple and the FBI fell out in 2016 after Apple refused to edit their phones' code to allow access so that the FBI could unlock the phone and read encrypted messages. WhatsApp received criticism from MPs in 2017 after a terrorist was found to have planned an attack in London using the service. WhatsApp messages are encrypted so that even WhatsApp themselves cannot read what its users have written to each other.